French Foreign Minister Laurent Fabius said early measures could include restrictions on visas, the assets of individuals and existing discussions on economic ties with Russia.
President Vladimir Putin on Tuesday defended Russia's actions in Crimea, which used to be Russian territory, and said he would use force only as a last resort.
This eased market fears of a war over the former Soviet republic after sharp falls on Monday, though Russian shares and the ruble slipped again on Wednesday, and Ukraine's hryvnia dropped against the dollar.
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Russian forces remain in control of Crimea, where Interfax reported they seized control of two Ukrainian missile defense sites overnight, and Putin gave no sign of backing down.
In Brussels, European Commission President Jose Manuel Barroso said EU deliver assistance to Kiev would in part be contingent on Ukraine signing an IMF loan deal, which will require painful economic reforms such as ending domestic gas subsidies and letting the hryvnia float.
"The package combined could bring an overall support of at least 11 billion euros over the next couple of years," Barroso told a news conference. The United States offered Ukraine $1 billion in loan guarantees on Tuesday.
G7 may meet soon
At his first news conference since the crisis began, Putin said on Tuesday that Russia reserved the right to use all options to protect compatriots who were living in "terror" in Ukraine but that force was not needed for now.
He told his cabinet on Wednesday he did not want political tension to detract from economic cooperation with Russia's "traditional partners." But the foreign ministry said Moscow was preparing counter-measures against Western firms if necessary.
(Read more: Ukraine worries?This economy is at risk too)
Canadian Prime Minister Stephen Harper said after speaking to Obama that the Group of Seven leading industrialized nations were considering meeting in the near future, a move that would exclude Russia, which joined what became the G8 in 1998.
Lavrov told European Union foreign policy chief Catherine Ashton that an EU-brokered agreement signed by political leaders in Kiev on Feb. 21 should be the basis for stabilizing the situation in Ukraine, his ministry said on Wednesday.
In Washington, Defense Secretary Chuck Hagel told Congress the U.S. military was stepping up joint training through an aviation detachment in Poland and boosting participation in a NATO air policing mission over the Baltic states, Estonia, Latvia and Lithuania—the only former Soviet republics that are members of the Western alliance.